Which bone is responsible for connecting the leg to the upper body?

The correct answer identifies the pelvis as being responsible for connecting the leg to the upper body. The pelvis serves as a crucial anatomical structure that supports the connection between the lower limbs and the trunk. It forms a basin-like structure that encases and supports pelvic organs and provides attachment points for muscles.

Specifically, the pelvis includes the hip bones, which contribute to the stability and mobility of the legs while also encapsulating the hip joints. This structure is essential in activities such as walking, running, and jumping, as it allows for the transfer of weight and movement between the upper body and the lower limbs.

In contrast, while the femur is the thigh bone connecting to the pelvis and the hip refers to the area surrounding the hip joint, neither of these options plays a direct role in connecting the leg to the upper body in the same manner as the pelvis. The sternum, located in the chest and serving as a key part of the rib cage, does not connect the leg to the upper body at all, making it an irrelevant option in this context. Thus, the pelvis is the appropriate answer as it functions as the critical bridge between the upper and lower sections of the body.